Preparation of a novel PdCl2-CuSO4-based ethylene scavenger supported by acidified activated carbon powder and its effects on quality and ethylene metabolism of broccoli during shelf-life

Yellowing and quality loss of broccoli is usually accelerated by ethylene. In order to remove ethylene surrounding the broccoli during shelf-life, a novel ethylene scavenger supported by acidified activated carbon powder (AACP) was developed. Results showed that acidification of the supporter might have a profound effect on ethylene scavenging. Ethylene removal rate of the palladium chloride (PdCl2)-impregnated AACP scavenger dramatically increased and was further promoted with the addition of copper sulfate (CuSO4). The novel scavenger was optimized and prepared with MCP containing 10 mg/g PdCl2, 30 mg/g CuSO4 and less than 300 mg/g moisture. Its maximum ethylene removal capacity was 21.77 mL/g at 25 degrees C or 20.18 mL/g at 5 degrees C. The ethylene removal capacity could be regenerated by 81.6% by heating at 175 degrees C for 20 min. The ACCP-PdCl2-CuSO4 ethylene scavenger could significantly delay yellowing and quality loss of broccoli and thereby extend the shelf-life at 20 degrees C for 2 d. Ethylene concentration in the stored environments was decreased to 0.21 mu L/L or less from 0.91 mu L/L during shelf-life by the scavenger. Ethylene production, free 1-aminocyclopropane-1-carboxylic acid (ACC) content and ACC synthase activity were suppressed in the broccoli treated with the scavenger. This ethylene scavenger might eliminate ethylene to lower levels in stored environments than the threshold to trigger senescence and yellowing of the vegetable. The novel scavenger provides a promising and eco-friendly alternative to maintaining postharvest quality of broccoli and contributes to increasing its marketing value. (C) 2014 Elsevier B.V. All rights reserved.